G. Wulff et S. Krieger, ON THE CHIRALITY OF POLYVINYL COMPOUNDS .17. INVESTIGATIONS ON MAIN-CHAIN CHIRAL COPOLYMERS WITH ALTERNATING STRUCTURE, Macromolecular chemistry and physics, 195(11), 1994, pp. 3679-3688
3,4-O-Cyclohexylidene-D-mannitol 1,2:5,6-bis-O-[(4-vinylphenyl)boronat
e] (M1) was copolymerized with methyl methacrylate (MMA) in presence o
f AlEt1,5Cl1,5 or SnCl4. The expected alternating bis(4-vinylphenylbor
onic acid)-MMA triad structures were only formed to a lesser extent. I
nstead, predominantly alternating 4-vinylphenylboronic acid-MMA struct
ures were obtained. Since no crosslinking was observed, a cyclocopolym
erization must have occurred. In this case an MMA unit is inserted bet
ween the two styrene residues of M1, thus forming a 21-membered ring s
ystem. Copolymerization forming alternating 4-vinylphenylboronic acid-
MMA diads is apparently even faster than the direct cyclopolymerizatio
n forming distryryl diads. After removal of the template (3,4-O-cycloh
exylidene-D-mannitol), these copolymers still show pronounced optical
activity and circular dichroism with a negative Cotton effect at 233 n
m. After deboronation of the copolymers, optically active, predominant
ly alternating styrene-MMA copolymers are obtained.